WO2019068545A1

WO2019068545A1 - Method for producing units with axially movable components

Info

Publication number: WO2019068545A1
Application number: PCT/EP2018/076237
Authority: WO
Inventors: Peter Hirschauer
Original assignee: Thyssenkrupp Presta Ag; Thyssenkrupp Ag
Priority date: 2017-10-05
Filing date: 2018-09-27
Publication date: 2019-04-11
Also published as: DE102017123161A1; US20200276766A1; US11813801B2; EP3691874A1; CN111183017A; EP3691874B1

Abstract

The invention relates to a method for producing an axially movable connection between two components betweeen which a plastic material is arranged as a sliding material, said method comprising the following features: a) providing the two components to be joined, either at least one of the two components comprising a plastic coating on the surface thereof facing the other component or a plastic sleeve being provided between the components; b) joining the components to form a unit, optionally with the plastic sleeve, by means of a pressing force in the axial direction; c) clamping the unit in a device in which the two shaft components can be mounted and subjected to a moving force in the axial direction; d) pressing a sonotrode from one side against the respectively outer component and supporting the component on a counter-holder; e) injecting an ultrasound signal into the sonotrode, and moving the shaft components back and forth in the axial direction until the moving force or the moving speed reaches a desired nominal value; and f) ending the ultrasound signal and removing the unit from the device.

Description

Method for producing assemblies with axially displaceable components

The present invention relates to a method having the features of the preamble of claim 1 and a motor vehicle steering system having the features of the preamble of claim 8.

Sliding joints for mutually displaceable components such. B. coaxial, mutually telescoping tubes or shafts that are rotatably inserted into each other and telescopic, are used in various fields of technology. The sliding connection should generally be low-friction, backlash-free and mechanically strong. Especially in motor vehicle steering such telescopic connections occur at various locations. There is on the one hand in the steering column itself a telescopic combination of an inner and an outer jacket tube, which surround a steering shaft and which are made telescopic for the axial adjustment of the steering column. In addition, the steering shaft itself, which transmits the driver's steering torque to the steering gear, is generally telescopic. Here, an approximately cloverleaf-shaped cross section, which is suitable for transmitting the torque, is used, so that the inner shaft part and the outer shaft part are positively engaged with each other in the direction of rotation. In both cases often becomes one

Plastic sleeve inserted between the two metal made, mutually displaceable components. It is problematic and costly in the production of these compounds that the plastic part can not be used directly as a component and without further

Processing steps can meet the requirements for backlash and a defined friction in the axial displacement movement.

In DE 26 35 120 AI a method for producing a sliding connection of a shaft is presented, in which an outer shaft and an inner shaft are pre-assembled with the interposition of a sleeve. Subsequently, the outer shaft is deformed inwardly, and with a sliding operation, the components are calibrated to each other. There is also a warming. The heating can be done with an induction heater, a gas flame or a contact heating, so that the plastic is brought into a plastic flow movement. The disadvantage here is the time required and the required thermal energy for heating the components out. Also, the end result is not satisfactory in all cases, as the shaft parts are heated and the geometry in the connection area changes again as a result of the cooling of the shaft parts after the above-described procedure.

No. 9,452,444 B2, a method for producing a telescoping shaft is presented, in which the two shaft parts, of which one of the two parts is coated with a plastic, are first assembled and then a displacement movement is triggered. The displacement force is measured. Subsequently, the shift is continued until a desired displacement force is reached. EP 2281731 Bl discloses a similar method. The disadvantage here are the relatively high forces that must be expended for calibrating the plastic layer. The long process time of the oscillating displacement movement and the complex apparatus requirements are disadvantageous.

It is therefore an object of the present invention to provide a method with which the process time can be shortened, a lower energy consumption is required and a better result can be achieved. This object is achieved by a method having the features of claim 1. It is a further object of the present invention to provide a device with mutually displaceable components, in which a better freedom of play and a more precise compliance with predetermined frictional forces or

Displacement forces are given. This object is achieved by a device having the features of claim 8.

The object is achieved in detail because in the method for producing an axially displaceable connection between two components, between which a plastic is arranged as a sliding material, the following features are provided:

a) providing the two components to be joined, wherein either at least one of the two components has a plastic coating on the surface facing the other component, or a plastic sleeve is provided between the components,

b) joining the components to form an assembly, optionally with the plastic sleeve, by means of a pressing force in the axial direction

c) clamping the assembly in a device in which the two shaft parts can be stretched and acted upon in the axial direction with a displacement force,

d) pressing a sonotrode from one side onto the respective outer component and supporting the component against a counter holder,

e) introducing an ultrasonic signal into the sonotrode and shifting the shaft parts in the axial direction back and forth until the displacement force or the

Shift speed reaches a desired setpoint,

f) terminate the ultrasonic signal and remove the assembly from the device.

This results in a faster and more precise calibration of the plastic sleeve or the sliding sleeve or the plastic coating in

Shifting range of components possible.

The object of such an axially displaceable connection between two components, in particular two cylindrical components, is to represent a displaceability with the lowest possible displacement force with at the same time little play between the components. In the event that the cylindrical components are to transmit torque as shafts, the highest possible torque should also be safely transmitted.

In particular, in this case, when torques are to be transmitted, the cross-sectional areas of the cylindrical components are deviating from a circular shape. It can then be provided for example corresponding grooves or teeth or grooves. In the design of such a connection, a maximum permissible force, which is required to represent a displacement of the two components against each other, set. This force then represents the desired value for the desired displacement force. It may also be provided to set the desired displacement value to a value that is 5%, preferably 10%, below the maximum permitted value for the displacement force specified in the design.

The desired setpoint for the displacement speed is determined by determining for a given displacement force, which is above the maximum permissible displacement force, in experiments in which

Speed of the desired setpoint for the displacement force is achieved. The setpoint for the speed is then set accordingly. Advantageously, a premium of 5%, and more preferably 10%, may be provided. Preferably, in the method, an ultrasonic signal having a frequency in the range of 20 kHz to 35 kHz is introduced into the sonotrode. More preferably, a frequency range of 25kHz to 30kHz is used.

It may be advantageous if the frequency of the ultrasonic signal introduced into the sonotrode is varied during the process sequence of the method.

Preferably, the components are a shaft inner part and a shaft outer part, in particular an inner steering shaft and an outer steering shaft of a

Motor vehicle steering system. It can also be provided that the components are an inner jacket tube and an outer jacket tube of an axially telescopic motor vehicle steering.

If two sonotrodes are pressed against the outer component in step d), a more intensive or otherwise parameterized introduction of energy is possible.

In particular, the two sonotrodes with ultrasonic signals

different frequencies are applied. Moreover, it has been shown that also with advantage more than two

Sonotrodes can be used to increase the energy input even further. A different frequency or another frequency characteristic over the process time can be applied to each sonotrode.

The ultrasonic power can also be determined separately for each sonotrode. Also courses can be provided. So, for a short start high power for up to 3 seconds and then low power for the remainder of the process time. The low power is advantageously 1/3 lower than the high power.

To illustrate the method for producing the axially displaceable connection, the displacement of the two components relative to one another preferably with a pneumatic cylinder, optionally with a hydraulic cylinder, are effected. Due to the introduced pressure can be done well a force-controlled movement of the clamped assembly. The force can also be set well for different speeds of movement and the displacement speed can be measured.

In motor vehicle steering with a telescopic steering shaft and / or a telekopierbaren casing tube unit, which is produced by a method described above, results in the production of shorter possible cycle times and a lower energy consumption. In addition, the motor vehicle steering is provided with better properties in terms of durability, freedom from noise and noise as a result.

Hereinafter, embodiments of the invention with reference to the

Drawing described. Show it :

Figure 1: a schematically illustrated motor vehicle steering; Figure 2-4: a lower steering shaft;

Figure 5-6: the steering shaft of Figure 2-4 in a cross section;

FIG. 7 shows the steering shaft from FIG. 5-6 in a longitudinal section during the

Calibration of the plastic sleeve;

Figure 8-9: another embodiment of a steering shaft; Figure 10: another embodiment of a steering shaft, an upper

Steering shaft;

FIG. 11: a jacket tube unit; Figure 12-13: the jacket tube in perspective view;

FIG. 14: the jacket tube from FIG. 12-13 in a cross section;

FIG. 15: the jacket tube from FIG. 11-14 during the calibration of the

Plastic sleeve; and FIG. 16 shows the steering shaft from FIG. 5-6 in a longitudinal section during the

Calibration of the plastic sleeve.

1 shows a schematic representation of a motor vehicle steering system 1 with a steering wheel 2, which is rotatably connected to an upper steering shaft 3. The upper steering shaft 3 is mounted vertically adjustable in a bracket 4 and axially adjustable. About a universal joint 5, the upper steering shaft is pivotally connected, but rotatably connected to a lower steering shaft 6. The lower steering shaft 6 is finally connected via a second universal joint 7 with a pinion 8, which engages in a rack segment 9 of a rack 10. A rotational movement of the steering wheel 2 thus leads to a shift in the

Rack 10 and in a known manner to a pivoting of steered wheels 11 of the motor vehicle, whereby a steering movement and direction change is effected.

The lower steering shaft 6 is shown in more detail in Figure 2. The same or functionally identical components carry the same reference numerals in the following figures.

The lower steering shaft 6 is provided with the first universal joint 5 and the second universal joint 7. The upper, first universal joint 5 is rotatably connected to a shaft inner part 15, while the second universal joint 7 is rotatably connected to a shaft outer part 17. The shaft outer part 17 has a rotationally symmetrical circumferential structure 18, which extends to a free end 19 of the outer shaft part 17. The structure 18 consists of straight grooves 20, which are impressed from the outside into the shaft part 17. The grooves 20 are parallel to the axis and give the shaft part 17 in cross section an approximately star-shaped structure. In the figure 3, the lower steering shaft 6 is shown in Figures 1 and 2 in a perspective view in which the shaft inner part 15 and the shaft outer part 17 are pulled apart. Here it can be seen that the shaft inner part 15 has at its free end 25 a region 26 which has a different shape from a circular cross-section. The cross-section of this region 26 is also characterized by grooves or grooves which give a star-shaped cross-sectional shape which match the free inner cross-section of the shaft outer valley 17. This will be described in more detail below. In the representation of FIG. 3, the shaft inner part 15 carries in the region 26 a plastic sleeve 30, which in the

Cross-sectional shape is adapted to the area 26.

This becomes clearer in FIG. 4 shows the lower steering shaft 6 in a representation corresponding to Figure 3, but with the plastic sleeve 30 is removed from the region 26 of the shaft inner part 15. The longitudinal axis and axis of symmetry 31 also represents the axial direction, in which the lower steering shaft 6 is designed to be telescopic.

The profiling of the lower steering shaft 6 in the areas in which the shaft inner part 15 and the shaft outer part 17 overlap and in which the plastic sleeve 30 is disposed between these two shaft parts results in a suitable design a non-rotatable, but in the direction of the longitudinal axis 31 telescopic connection. In the case of the lower steering shaft 6, such a telescopic connection is advantageous because the steering gear with the

Rack 10 is installed in the region of the front axle of the motor vehicle, while the steering column 1 is attached approximately in the region of the dashboard to the body. Relative movements of these attachment points are unavoidable when driving the motor vehicle. These relative movements are due to the illustrated construction of the lower steering shaft. 6

added. It is important for the function and ride comfort that the connection between the two shaft parts works permanently backlash-free and yet low-friction. For this purpose, a precise adjustment of the plastic sleeve 30 to the two profiles on its inside and the outside is required. The inventive method, this Adjustment in a particularly advantageous manner, will be described in more detail below.

FIG. 5 shows the lower steering shaft 6 in a cross-section in FIG

profiled area, schematized in a mounting situation. The shaft inner part 15 and the shaft outer part 17 are pushed into one another in their mating, profiled area. Between the inner surface of the shaft outer part 17 and the outer surface of the shaft inner part 15 is the plastic sleeve 30, which sits there backlash. In order to ensure the backlash, the plastic sleeve 30 is provided with an oversize, so that the first seat of the two shaft parts in one another has high friction. In operation, this high friction would be adversely affected by unwanted forces and also by noise due to the stick-slip effect. To adapt or calibrate the plastic sleeve 30 to the exact dimensions of the two shaft parts is provided during manufacture, a sonotrode 35 set up in a radial direction on the shaft outer part 17. An anvil 36 is attached to the opposite side of the shaft outer part 17. The shaft outer part 17 is thereby firmly clamped between the sonotrode 35 and the anvil 36. FIG. 6 shows a similar arrangement to FIG. 5. In contrast to FIG. 5, it is provided in FIG. 6 that the sonotrode 35 and the anvil 36 are not inserted into the grooves 20 of the shaft outer part 17, but on outer surfaces formed between the grooves 20 37 are attached.

FIG. 7 shows, in a longitudinal section, the embodiment according to FIG. 5, the sonotrode 35 and the anvil 36 being again inserted into a respective groove 20 of the shaft outer part 17. The shaft inner part 15 is inserted into the plastic sleeve 30 and the shaft outer part 17. Both shaft parts are now detected by collets 40 and 41. A control and evaluation unit 68 takes over the process control. The sonotrode 35 is driven by a controller 66 to transmit an ultrasonic vibration to the outer shaft part 17. The outer shaft part 17 is thereby set in a mechanical vibration Since the shaft outer part 17 itself relatively free vibrates, the vibration energy is transferred to a large extent on the plastic sleeve 30, which is thereby deformed at a high frequency. The plastic sleeve 30 heats up. At the same time by a relative movement in the direction of the double arrow 42 by means of the collets 40 and 41 of the inner shaft member 15 reciprocated in the axial direction. The heated plastic sleeve 30 adapts to the two facing each other

Surfaces of the shaft inner part 15 and the shaft outer part 17 at. The adjustment operation can be controlled by measuring the displacement force to be applied by the collets 40 and 41 in the reciprocation. For this purpose, a force transducer 65 may be provided. Preferably, the heating of the plastic sleeve 30 by means of ultrasound as well as the movement in the direction of the double arrow 42 is carried out until a maximum displacement force is exceeded. The fitting process is then completed. After switching off the excitation of the sonotrode 35, the plastic sleeve 30 cools down quickly, since the two shaft parts 15 and 17 were not heated by the ultrasonic excitation substantially themselves and thus are compared to the plastic sleeve 30 cold. This promotes the dimensional accuracy of the calibrated plastic sleeve 30. In addition, the shaft outer part 17 and the shaft inner part 15 in this process undergo virtually no thermal changes in their dimensions. In contrast, the shaft outer part was heated in conventional methods and cooled down again after the calibration process, whereby the achievable precision of the calibration process of the plastic sleeve 30 is limited. The warm-up and cool down times of the process described are due to the low mass to be heated, the plastic sleeve 30 short, so that a short cycle time can be achieved. Furthermore, it is sufficient to heat the plastic sleeve only on the surface so far that they can mold well.

The method described above is not limited to profiled shafts such as the lower steering shaft 6, in which both the shaft inner part 15 and the

Shaft outer part 17 are profiled, applicable. Thus, Figures 8 and 9 show another embodiment of a telescopic steering shaft 50 with a shaft inner part 51 and a shaft outer part 52, which in the direction of Longitudinal axis 53 telescopically joined together. The inner shaft part 51 has an end-side region 54 which is surface-coated. For calibrating this surface coating in the above-mentioned sense, the method described in connection with FIGS. 5 to 7 can also be applied to such a shaft.

However, it should also be noted that such a telescoping in their length connection in the case of the upper steering shaft 3 may be useful, as shown in Figure 10. In the case that the steering wheel 2 is displaceable to the console 4, such telescopic connections are used for the upper steering shaft. All variants and embodiments illustrated with reference to the lower steering shaft 6 are equally applicable to the upper steering shaft 3. Accordingly, the upper steering shaft 3 may have an inner steering shaft 71 and an outer steering shaft 72 with the interposition of a sleeve 74 and be telescopically joined together in the direction of a longitudinal axis 73. For calibrating this connection, the method described with reference to FIGS. 5 to 7 can also be applied to the upper steering shaft 3.

FIGS. 11 to 15 show an example of a telescoping jacket tube unit 60. The telescopic casing tube unit 60 has the upper steering shaft 3, which has been described above for Figure 1 and Figure 10. The upper steering shaft 3 is mounted in an inner jacket tube 61 and an outer jacket tube 62. For axial adjustment of the steering column while the inner shaft portion 71 and the outer shaft portion 72 of the upper steering shaft 3 are slidably formed in its longitudinal axis 73, as explained with reference to FIG. Next is for axial adjustment of the steering column, the inner

Jacket tube 61 relative to the outer casing tube 62 in the axial direction, which corresponds to the longitudinal direction of the longitudinal axis 73, slidably formed.

Between the inner casing tube 61 and the outer casing tube 62, a sliding sleeve 63 is provided, which is shown separately in Figure 12. The sliding sleeve 63 is seated between the inner jacket tube 61 and the outer jacket tube 62, as can be seen in FIG. It is at the inner

Jacket tube 61 and the outer jacket tube 62 in the technical sense not to waves, as they have a circular cross-section and no Can transmit torques. It is nevertheless advantageous for the reasons mentioned above, if the seat of the two casing pipe parts in the region of the sliding sleeve 63 is free of play and yet smooth. For this purpose, the method described for FIG. 7 is also used for calibrating the sliding sleeve 63 between the inner jacket tube 61 and the outer jacket tube 62. This is illustrated in FIG. The sonotrode 35 is placed externally on the outer jacket tube 62, which is supported on the oppositely placed anvil 36. Then, the sonotrode 35 is again controlled by a controller 66 with electrical voltage of a specific frequency or a frequency response. The vibrational energy in turn leads to a heating of the sliding sleeve 63.

FIG. 15 illustrates that during the process, the inner jacket tube 61 is clamped between clamping jaws 40, while the outer jacket tube 62 is clamped between clamping jaws 41. While the

Sliding sleeve 63 is heated, the inner casing tube 61 is reciprocated in the direction of the double arrow 42. The required displacement force F is detected by a force transducer 65. The displacement force F decreases with the number of strokes in the direction of the double arrow 42. Once a certain threshold is reached or fallen below, the calibration of the sliding sleeve 63 is completed. The control of the process takes place again via the control and evaluation unit 68. The casing tube unit 60 thus processed is then removed from the collets 40 and 41, the anvil 36 and the sonotrode 35 are removed, and the jacket tube can be placed in a console 4 according to FIG to be built in. As shown in Figure 10 is shown in this embodiment that the upper steering shaft 3, which is mounted in the telescopic casing tube, also has a sliding connection, wherein the sliding connection may correspond to the embodiments of Figures 2 to 9 and is adapted to transmit torques. Alternatively or in combination with the use of a force transducer 65, a speed sensor 67 may be provided, which may also be designed as a displacement transducer, the speed being determined in a control and evaluation device 68. This is illustrated in FIG. FIG. 16 shows, analogously to FIG. 7, a longitudinal section of the embodiment according to FIG. 5, wherein the sonotrode 35 and the anvil 36 are again inserted into a respective groove 20 of the shaft outer part 17. The shaft inner part 15 is in the plastic sleeve 30 and the shaft outer part 17 is inserted. Both shaft parts are now detected by collets 40 and 41. The collet 41 is held stationary while the collet 40 by a

Pneumatic cylinder can be acted upon with a movement. A

Control and evaluation unit 68 assumes the process control. The sonotrode 35 is driven by a controller 66 to transmit an ultrasonic vibration to the outer shaft part 17. The outer shaft part 17 is thereby set in a mechanical vibration. Since the shaft outer part 17 oscillates relatively freely itself, the vibration energy is transferred to a large extent on the plastic sleeve 30, which is thereby deformed at high frequency. The plastic sleeve 30 heats up. At the same time by a relative movement in the direction of the double arrow 42 by means of the collets 40 and 41 of the inner shaft member 15 reciprocated in the axial direction. For this purpose, the pressures pl and p2 are alternately increased and decreased, so that the piston 69 is moved back and forth. The piston 69 is mechanically coupled to the Spannzahnge 40 accordingly. The heated plastic sleeve 30 adapts to each other

facing surfaces of the shaft inner part 15 and the shaft outer part 17 at. The adjustment operation may be controlled by detecting the speed at which the collet 40 is moved with a displacement sensor or speed sensor 67. Preferably, the heating of the plastic sleeve 30 by means of ultrasound as well as the

Movement in the direction of the double arrow 42 executed until the

Maximum value of the shift speed exceeds a designated minimum setpoint. The fitting process is then completed. This process sequence also offers the advantages already mentioned. The sequence of operations described above thus provides as an exemplary embodiment the following partially optional process steps:

- Providing the two shaft parts to be joined, wherein either at least one of the two shaft parts has a plastic coating on the surface facing the other shaft part,

or a plastic sleeve is provided for abutment between the shaft parts,

- Assembling the shaft parts, possibly with the plastic sleeve in between,

- Wherein the shaft parts and optionally the plastic sleeve are formed so that the joining can be done only by overcoming a pressing force, since the sliding seat is formed with an oversize,

- Clamping the assembly in a device in which the two

Shaft parts tensioned and can be acted upon in the axial direction with a displacement force. The device is preferably equipped so that a displacement force can be measured.

- Pressing a sonotrode from one side to the outer one

Shaft part and supporting the inner part of a counter-holder

(Anvil),

- Introducing an ultrasonic signal in the sonotrode and moving the shaft parts in the axial direction back and forth until the displacement force reaches a desired target value. Alternatively, the method can be carried out so that with a constant force, the shaft parts are shifted from each other and the displacement speed is measured. Then the process is terminated when a certain shift speed is reached.

- After completion of the process, the shaft is removed as a finished component of the device and further installed.

Claims

claims

1. A method for producing an axially displaceable connection between two components, between which a plastic as

Sliding material is arranged, with the following features:

a) providing the two components to be joined, wherein either at least one of the two components has a plastic coating on the surface facing the other component or a plastic sleeve is provided between the components, b) joining the components to form an assembly, optionally with the plastic sleeve, by means of a pressing force in the axial direction c) clamping the assembly in a device in which the two shaft parts can be tensioned and acted upon in the axial direction with a displacement force,

e) introducing an ultrasonic signal into the sonotrode and

Moving the components in the axial direction back and forth until the

Displacement force or the displacement speed

desired setpoint reached,

f) terminate the ultrasonic signal and remove the assembly from the device.

2. The method according to any one of the preceding claims, characterized in that the frequency of the sonotrode

introduced ultrasonic signal in the range of 20 to 35 kHz.

3. The method according to any one of the preceding claims, characterized in that the frequency of the sonotrode

introduced ultrasonic signal during the process flow of the method is varied.

4. The method according to any one of the preceding claims, characterized in that the components have a shaft inner part and a Shaft outer part, in particular an inner steering shaft and an outer steering shaft of a motor vehicle steering are.

5. The method according to any one of the preceding claims, characterized in that the components are an inner jacket tube and an outer jacket tube of an axially telescoping

Motor vehicle steering are.

6. The method according to any one of the preceding claims, characterized in that in step d) two sonotrodes are pressed against the outer component.

7. The method according to claim 6, characterized in that the two sonotrodes are subjected to ultrasonic signals of different frequencies.

8. Motor vehicle steering with a telescopic steering shaft (3, 6) and / or a telekopierbaren casing tube unit (60), which is prepared by a method having the features of the preceding claims.